The Lexile Framework for Reading is a scientific approach to measuring both text difficulty and reading ability on a scale that was developed by MetaMetrics®. Each student who takes the WESTEST 2 receives a Lexile® measure with his/her test score results. The measure will be represented as a number with an L after it, such as 750L.

There are two Lexile measures: the Lexile reader measure and the Lexile text measure. The Lexile reader measure represents the student's reading ability and the Lexile text measure represents the difficulty of the text. When used together, they can help a reader select reading material that is at an appropriate difficulty level. The Lexile reader measure can be used to monitor growth in reading ability over time.

A reader's Lexile range is from 50L above to 100L below the reader's Lexile score. If a student attempts reading material above his/her Lexile range the challenge may be too great for the student to master independently. In a classroom setting where textbooks are used as the main reading material, the texts may not be well-matched to all students. West Virginia is now asking that all textbooks on the state adoption list have a Lexile score.

The Lexile measure (text complexity) of a book is an excellent starting point for a student’s book selection. It’s important to understand that the book’s Lexile measure should not be the only factor in a student’s book selection process. Lexile measures do not consider factors such as age-appropriateness, interest, and prior knowledge. These are also key factors when matching children and adolescents with books they might like and are able to read. Lexile codes provide more information about developmental appropriateness, reading difficulty, and common or intended usage of books. For more information on Lexile codes, please visit Lexile.com/about-lexile/lexile-codes/.